While workers in Burlington last month rushed to contain a huge spill of sewage liquids and downstream governments monitored their drinking water, no one reached out to the boaters who paddle the Haw River in the winter.

A week later, Duke Energy waited 26 hours to give public notice of an ongoing spill that filled the Dan River with millions of pounds of coal ash. Ten days after the leak was found, the state warned residents not to touch the sludgy material or eat fish from the river.

Environmentalists, some scientists and public officials downstream of the sites say the public needs to be alerted faster of potential health hazards. State Senate leader Phil Berger, a Republican from Eden, a community on the Dan River, has called for a legislative inquiry into both incidents.

He's "very concerned about the quality and timeliness of the responses of everyone involved," according to his office.

In recent interviews, two water-quality scientists said that a lack of warning can leave boaters and swimmers vulnerable to potentially dangerous materials.

"It's inappropriate to assume that there's no increased risk to recreaters who come in contact with the water if that discharge of sewage is still present in the water," said Mark Sobsey, director of the Environmental Microbiology Laboratory at the University of North Carolina at Chapel Hill, referring to the Haw River spill.

The town of Carrboro likely will push for a change in public-notice laws, said Randee Haven-O'Donnell, a member of the town's elected board. To her and others, the idea of waiting to announce an ongoing spill of sewage or industrial contaminants is incongruous with modern styles of communication.

"We live in a time now where you can instantly alert folks that this situation has occurred, that you don't have all the information, but you want them to stay away from being in the river, whether they're fishing or they're kayaking," Haven-O'Donnell said. Her town is near the Haw and may eventually use it for drinking water.

On the other side, state officials argue that they are vigilant about public health and that notifications in both the Haw and Dan spills met requirements of state law.

North Carolina law allows 48 hours for public notice, but the Department of Health and Human Services can intervene earlier, as it's tasked with identifying and responding to health concerns, including spills.

Burlington's spill began on the night of Jan. 26, when pressurized sewage erupted from about 8 feet underground, spraying from a crack in the main sewage line serving the East Burlington Wastewater Treatment Plant.

The city's emergency equipment wasn't powerful enough to handle the incoming sewage, so the raw effluent instead flooded from large manholes in a wooded area near the Haw, said Robert Patterson, director of water resources for the city.

It was "somewhere between a trickle and a gush," Patterson said. The design of the manholes prevented waste solids from overflowing, but wastewater contains bacteria and pollutants, said a spokeswoman for the state Department of Environment and Natural Resources.

"It would kind of roll out the sides over the manhole, and then run across the ground onto a low point," Patterson said.

The flood continued from that Monday night until Wednesday afternoon, surging with heavier sewer usage. It ranks among the 50 largest sewer spills in the state's recent history, according to state records.

It's not clear when the sewage touched the Haw, but the state is standing by estimates that 3.5 million gallons flowed into the river.

DENR was informed Monday night, but no DENR representative visited the site until Thursday. Still, DENR officials told the city to hold off on a public notification, and even to wait beyond the legal 48-hour window.

"They said, 'Let's wait till we get it stopped.' We were in constant conversation," Patterson said.

He largely agrees with that approach: "I think you always want to give the most complete picture that you can. At that point, we weren't sure when exactly the flow is going to stop."

The Department of Health and Human Services, which is responsible for public health hazards, did not contact Patterson's department, he said. City and county officials were aware of no effort to post signs at the places boaters typically enter the river.

Corey Basinger, a regional supervisor for the Division of Water Resources within DENR, said that freezing temperatures likely minimized bacterial growth and the accompanying health threat. He and DENR spokeswoman Susan Massengale also said that the Haw's high flow would dilute the effluent, and that cold temperatures and ice on the river minimized recreation.

Joe Jacob, who owns Haw River Canoe & Kayak Co., said that high-water flows in winter actually draw paddlers to the river.

"If their kid would've been paddling the river that day, they sure would have wanted to know about it," the paddling guide said. And Sobsey, the UNC-CH professor, said that while cold temperatures help, raw sewage can remain a dangerous and pathogen-infested material for days or even weeks after its release.

"Raw sewage could easily have 100 million fecal coliform bacteria per 100 milliliters, compared to a limit of a few hundred for treated effluent," he said.

With that kind of concentration, a boater on the Haw who touched or swallowed the water could have contracted a gastrointestinal or respiratory illness, among other possibilities, Sobsey said.